It was narrated from 'Aishah (may Allah be pleased with her) that Umm Habibah, an in-law of the Messenger of Allah (ﷺ), who was married to 'Abdur-Rahman bin 'Awf, suffered Istihadah (non-menstrual vaginal bleeding) for seven years. She consulted the Prophet (ﷺ) about that and the Messenger of Allah (ﷺ) said:
'That is not menstruation, rather that is a vein, so perform Ghusl and pray.'"
English reference: Vol. 1, Book 1, Hadith 205
Arabic reference: Book 1, Hadith 206